上软下硬地层大跨无柱地铁车站地震响应分析

Analysis of Seismic Response of Large-span Column-free Metro Station Structure under Upper-soft and Lower-hard Composite Strata

为研究大跨度无柱地铁地下车站结构在上软下硬地层中的地震响应,以广州地铁11号线为依托工程,采用ABAQUS软件开展该类复合地层中车站结构的震害规律分析,对比研究软硬地层交界面处于车站结构不同位置时结构地震动响应特性的异同及规律。结果表明:1)在强震作用下,软硬交界面分别位于中板上下两侧时结构的损伤程度、最大相对水平位移、残余变形量及摆动形态均有很大差异;2)随着地震波峰值加速度的增大,交界面处于中板及以下时,其位置的变化造成车站结构地震响应的变化程度比交界面处于中板及以上时有大幅增长;3)车站结构顶板相对底板的加速度放大系数与地震波大小及软硬地层交界面的埋深密切相关;4)车站结构的地震响应随软硬地层间剪切模量比值的变化在一定范围内产生较大变化,当剪切模量比值小于1/40时,地震响应的变化趋势将不再显著。

The rules of seismic response of large-span column-free metro station under upper-soft and lower-hardcomposite strata are studied by software ABAQUS based on Guangzhou Metro Line No. 11. Six cases are set withinterface between soft and hard strata horizontally implemented in different positions of station structure. Andcomparisons on seismic response of structure among different cases are analyzed. The results show that： 1） As interfacepositioning above or below middle slab of station structure, seismic response, i. e. damage degree, maximum relativehorizontal displacement, residual deformation and shaking form, are distinguished under strong seismic. 2 ） Withincrement in peak acceleration of seismic wave, variation of structure′s seismic response caused by interface′s positiongains more augmentation when interface positioning above middle slab than below. 3 ） Amplification coefficient ofacceleration between roof slab and bottom slab is closely related to size of seismic as well as thickness of soft stratum. 4）Ratio of shear modulus between different strata has an effect on seismic response of metro structure to a certain degree.When ratio is smaller than 1 / 40, stabilization is observed on the difference of seismic response.